This invention relates to a submersible electric motor, and more particularly to improvements in a sealing device operatively associated with a submersible electric motor comprising a molded member encapsulating a stator except for the inner surface provided with a can and connected to a bracket through a socket and spigot joint so as to block a stream of a cooling and lubricating liquid flowing within the bracket and that of ambient water across the molded member and the can.
A conventional submersible electric motor of the type referred to has comprised a stator including a molded member of a synthetic resin encapsulating the main body of the stator except for the inner cylindrical surface thereof and burying an associated electric component in one end portion thereof, the molded member having an inner cylindrical surface flush with that of the main stator body except for both end portions thereof, a hollow cylindrical can of, for example, thin sheet stainless steel disposed on the inner cylindrical surfaces of the molded member and the main stator body, a molded bracket connected to the end portion of the molded member through a socket and spigot joint, the bracket journalling a rotor shaft and enabling a cooling and lubricating liquid to flow therein, and an annular sealing member inserted into a circumferential groove disposed on that end portion of the bracket inserted into the molded member to engage the can.
This sealing member has been effective for preventing the cooling and lubricating liquid which comes between the can and the bracket from the rotor side and then reaches the same, from going over the sealing member. On the other hand, ambient water might come between the molded member and the bracket until it reaches the end surface of the can. Then the water has been divided into one portion which comes between the can and the bracket, and the other portion which comes between the molded member of the stator and the can. The one portion of the water has reached the sealing member after which it is prevented from further advancing between the bracket and the can by means of the sealing member. On the other hand, the molded member of the stator and the can have included respective joined surfaces exposed to the other portion of the water. If an exfoliation occurs between the joined surfaces of the molded member and the can then the other portion of the water reaches the exfoliated surface portion to further facilitate the exfoliation of the molded member from the can as well as causing the water to penetrate the molded member of the stator through the exfoliated surface portion or portions. This has resulted in the disadvantage that the electric component buried in the molded member decreases in insulation resistance.
Accordingly, it is an object of the present invention to provide in a submerged electric motor such as described above, a new and improved sealing device retaining the advantages of the prior art practice that the cooling and lubricating liquid is prevented from flowing out of the electric motor and ambient water is prevented from flowing into the interior of the electric motor, and furthermore effective for preventing ambient water having come between abutting surfaces of the molded member of the stator and the bracket from advancing between the can and the molded member.